Manufacturing method of insulated wire

ABSTRACT

This invention relates to a manufacturing method of insulated wire by electrodeposition coating. More particularly, it relates to a manufacturing method of insulated wire by electrodeposition coating which is characterized in that after the electrodeposition of a resin, the coated wire is treated with a solution or dispersion of a surface active agent or solid lubricant in a solvent.

United States Patent Masuda et al.

Oct. 1, 1974 MANUFACTURING METHOD OF INSULATED WIRE Inventors: ShigeoMasuda, Osaka; Masahiro Izumi, Nagoya, both of Japan Assignee: SumitomoElectric Industries Ltd.,

Osaka, Japan Filed: Jan. 17, 1972 Appl. No.: 218,575

Foreign Application Priority Data Feb. l8, 1971 Japan 46-7511 US. Cl.204/181 Int. Cl B0lk 5/00, C23b 13/00 Field of Search 204/ 181 [56]References Cited UNITED STATES PATENTS 3,540,990 l1/l970 Onishi et al204/181 3,681,224 8/1972 Stromberg 204/181 Primary ExaminerHoward S.Williams Attorney, Agent, or FirmCarothers and Carothers 5 7 ABSTRACT 1Claim, N0 Drawings MANUFACTURING METHOD OF INSULATED WIRE BACKGROUND OFTHE INVENTION This invention relates to a manufacturing method ofinsulated wire. More particularly, it relates to imparting an excellentcoiling property to insulated wire insulated by an electrodepositioncoating process.

In the case of magnet wire heretofore manufactured, varnish is appliedby means of dies, wiper rollers, felts, etc. and is baked. The desiredproperties are obtained by repeating this procedure. When manufacturingmagnet wire by an electrodeposition coating process, however, varnish isapplied only once and is baked, so that it is necessary to obtain a filmof the desired thickness by one application. At the same time, it isnecessary to obtain the desired properties by baking only once. Althoughthe manufacture of magnet wire by an electrodeposition coating processhas been studied at length and developed in many quarters in recentyears, it cannot yet be said satisfactory with respect to the propertiesobtained as compared with those obtained by the conventional method.That is to say, since magnet wire manufactured by an electrodepositioncoating process undergoes the coating process only once, its coatingfilm is liable to have various defective portions. As a result, suchwire is frequently found inferior to wire manufactured by theconventional method with respect to breakdown voltage, resistance tofriction, thermal softening, etc. On the other hand, when the magnetwire is used for coils, coiling is done in most cases by an automaticcoiling machine. At that time the magnet wire is subjected to a greatmechanical stress, so that it is often the case that the film isimpaired and the properties of the magnet wire after coiling are furtherlowered. Although a solution to this problem is to provide the coilingmachine with such a mechanism that it will not impair the magnet wire,an alternative solution is to impart to the magnet wire itself anexcellent coiling property.

BRIEF DESCRIPTION OF THE INVENTION By imparting an excellent coilingproperty to magnet wire manufactured by an electrodeposition coatingprocess and thereby eliminating mechanical impairment to the coatingfilm by an automatic coiling machine of severe working conditions, thisinvention imparts to the magnet wire coated by electrodeposition a fulldependability for use in electric machines and appliances in general,even if such wire is inferior to magnet wire manufactured by theconventional method with respect to general properties.

What is called, the coiling property of magnet wire is as follows. Whenmagnet wire is coiled to make coils for the rotary part of a motor orstators, it is coiled to some desired shape by an automatic coilingmachine. At that time, the magnet wire is subjected to great tension, sothat friction may take place between turns of the magnet wire or betweenthe magnet wire and the metallic core or between the magnet wire and thestator metal. As a result, the coating film of the magnet wire becomesmechanically impaired.

For this reason, magnet wire having a good coiling property is generallyone having a small friction coefficient. Mechanical impairment to magnetwire is minimized by lowering this friction coefficient as far aspossible. We have improved the coiling property of magnet wire bydecreasing the friction coefficient of the magnet wire.

In the case of magnet wire having an electrodeposition coating, acoating film of a desired thickness must be obtained by applying thevarnish once, so that it is quite conceivable, and has actually been thefact, that it is mechanically, electrically and chemically inferior tosuch wire manufactured by the conventional method which entailslaminating thin layers one upon another.

There are two kinds of varnishes for an electrodeposition coating. Oneis a varnish in the state of a complete solution in a solvent, and theother is one in the state of a dispersion in a solvent. With regard totheir characteristics, it may generally be said that varnishes of thesolution type have a very good adhesive property. In the case of simplecoatings as for magnet wire, however, a good adhesive property is not soadvantageous. A cause of this good adhesive property is a very highinsulation resistance of the electrodeposited film (before baking). Whenthe film deposited becomes thick, its insulation resistance makes itimpossible to I have the film deposited to be more than a certainthickness. This is a serious drawback for the manufacture of magnet wirewhich requires a comparatively large thickness. That is to say, withvarnishes of the solution type, it is difficult to obtain a coating filmof a desired thickness. To the contrary, it is comparatively simple toobtain a film of a desired thickness with varnishes of the dispersiontype. However, they have shortcomings that they lose luster at the timeof baking and in that the coating is liable to become cracked. Togetherwith these shortcomings, they have a fatal defect in that it isdifficult to obtain a smooth surface and consequently the coilingproperty of the wire is low.

A point of this invention is that a surface active agent or a solidlubricant which lowers the friction resistance is caused to permeate anddisperse among varnish particles before baking and an excellent coilingproperty is thereby imparted to the magnet wire.

In order to improve the coiling property of magnet wire by lowering thefriction coefficient of the insulating coating, a method entailing theapplication of a lubricating oil to the magnet wire in a thin layerafter baking has heretofore been employed. However, that method has beenfound to be rather troublesome, as it is necessary to pay considerationto the kind and quantity of oil to be used.

The attaching of a solid lubricant to the coating film after baking isquestionable with respect to the uniformity of the application, and itis not a good method if the loss of lubricant is taken into account.There is a method in which a lubricant is previously added to thevarnish. This is effective with the conventional method of die drawingor of felt squeezing, but is not very effective when manufacturingelectric wire by electrodeposition coating.

The reason for this is that even if a surface active agent or solidlubricant is dissolved or dispersed in a water varnish, the solvent inthe varnish is affected by the action of electric osmosis when the resinin the varnish is electrodeposited on the conductor, so that it ismostly discharged from the electrodeposited resin and scarcely remainsin the electrodeposited resin. It therefore is not effective, even if itcan be dissolved or dispersed in the water varnish before hand. Thetreatment step for rendering a good coiling property which is ES 282 dmo26 Z 262 45m R H 2 2 JEN);

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This invention is effective on varnishes of both the solution type andthe dispersion type, and gives an ex- 5 cellent coiling property tomagnet wire with an electrodeposited coating.

DETAILED DESCRIPTION OF THE INVENTION Now this invention will beexplained in detail.

An electrodeposited resin contains solid in a concentration of 80 90percent. The resin is baked in a baking furnace. According to thepresent invention, a solvent treatment vat for giving a treatment to thecoated wire to render an excellent coiling property is provided 15between the electrodeposition vat and the baking furnace. As for thesolvent used, it is preferable to use a solvent which has an actionwhich will help a surface active agent or solid lubricant penetrate intothe electrodeposited resin.

A point of the present invention is that a surface active agent or solidlubricant which lowers the friction coefficient of the coating film ofthe magnet wire is added to such a solvent in a suitable quantity.

If the resin electrodeposited in this way is given such a treatmentbefore baking, the coiling property of the magnet wire obtained is foundto be exceedingly good. While temperatures which are not below roomtemperature may be satisfactory for the treating vat, it is preferableto raise its temperature to about 60 90 C. to obtain a better effect. Itis possible thereby to have the surface active agent or solid lubricantpenetrate into the coating film in a very short time and obtain, afterdrying, magnet wire having an excellent coiling property with a smallfriction coefficient. There are many surface active agents which may beused, but those which are most effective are silicon compounds.

They are, for example, those of the type such as Paintat of FujiKobunshi and KPX" of Shinetsu Kagaku. Such surface active agents act tolower surface tension, and, in the coating film after baking, lowers thefriction coefficient.

As solid lubricants, there are both inorganic and organic substances,such as graphite, molybdenum disulphide, lead oxide,polytetrafluoroethylene, etc. To ensure a better effect, it ispreferable to use one which dissolves and penetrates into theelectrodeposited resin together with the solvent rather than one whichmerely disperses in the solvent.

For example, there are the solid type as solid of tetrafluorocarbonmanufactured by the 3M Company.

By dissolving a very small quantity of such a silicon or fluorocarbonproduct, the friction coefficient of the magnet wire can be lowered andimpairment to the coating film done by the automatic coiling machine isfor the most part prevented. If the additive is in a quantity of about0.0l 1 percent, it proves effective, but there are no limits to itsquantity in so far as affecting the properties of the coating film.

When the static friction coefficient of magnet wire in general ismeasured, it is found to be about 0.09 0.12 with all of the commonpolyvinylformal wire, polyester wire, polyamideimide wire,polyesterimide wire, etc.,

while on the other hand the static friction coefficient of nylon wireand wire with nylon overcoating is about 0.04 0.08. The presentinvention is a success in lowering the friction coefficient of 0.09 0.10to about one half, 0.05 0.06, by having a silicon compound or fluorideresin in the coating film of the magnet wire by the method of thisinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Explanation will now be givenwith reference to examples.

Example for Comparison 1.

The electrodeposition vat was filled with a polyester water-solublephenol varnish modified with maleic acid, and a treating vat of a lengthof 30 cm was provided between the baking furnace and theelectrodeposition vat.

N-methyl-Z-pyrolidone was used as the principal solvent of the treatingliquid. The temperature of the treating liquid was 40 C. Themanufacturing conditions and properties are given in the table.

Example for Comparison 2.

The electrodeposition vat was filled with Lecton RK- 6338 of Du-Pont,whose principal component is acrylonitrile. The principal solvent forthe treating liquid was N-methyl-Z-pyrolidone. The temperature of thetreating liquid was 70 C. The manufacturing conditions and propertiesare given in the table.

Example for Comparison 3.

The electrodeposition vat was filled with a varnish of the dispersiontype, the principal component of which was polyvinylformal.

N-dimethylacetamide was used as the principal solvent for the treatingliquid, and the temperature of the treating liquid was 70 C. Themanufacturing conditions and properties are given in the table.

Example of embodiment l.

In employing the method of Example for comparison I, Paintat M, asilicon surface active agent of Fuji Kobunshi, was added to the treatingliquid in a quantity of 0.5 percent. The coating film of the magnet wirehad a smaller friction coefficient, and its coiling property was foundimproved.

The manufacturing conditions and properties are shown in the table.

Example of Embodiment 2.

Fluorocarbon FC-98, a solid lubricant of 3M Company, was added in aquantity of 0.3 percent to the treating liquid of the method of Examplefor Comparison 1. The friction coefficient became smaller and thecoiling property was improved. The manufacturing conditions andproperties are shown in the table. Example of Embodiment 3.

KPX-32l, a surface active agent made by Shinetsu Kagaku, was added in aquantity of 0.5 percent to the treating liquid of the method of Examplefor Compari- 7 son 2. Magnet wire having a good coiling property wasmanufactured.

The manufacturing conditions and properties are shown in the table.Example of Embodiment 4.

Paintat M, a surface active agent made by Fuji Kobunshi, was added in aquantity of 0.5 percent to the treating liquid of the method of Examplefor Comparison 2. Magnet wire having a good coiling property wasmanufactured.

The manufacturing conditions and properties are shown in the table.

Example of Embodiment 5.

Fluorocarbon FC-95, a solid lubricant made by 3M Company, was added in aquantity of 0.3 percent to the treating liquid of the method of Examplefor Comparison 2.

Magnet wire having a good coiling property was manufactured.

The manufacturing conditions and properties are shown in the table.

Example of Embodiment 6.

KPX-32l, a surface active agent made by Shinetsu Kagaku, was added in aquantity of 0.5 percent to the treating liquid of the method of Examplefor Comparison 3. Magnet wire having a good coiling property wasmanufactured.

The manufacturing conditions and properties are shown in the table.

Example of Embodiment 7.

Paintat L, a surface active agent made by Fuji Kobunshi, was added in aquantity of 0.5 percent to the treating liquid of the method of Examplefor Comparison 3. Magnet wire having a good coiling property wasobtained.

The manufacturing conditions and properties are shown in the table.

Example of Embodiment 8.

Fluorocarbon FC-l34, a solid lubricant made by 3M. Company was added ina quantity of 0.3 percent to the treating liquid of the method ofExample for Comparison 3. Magnet wire having a good coiling property wasmanufactured.

The manufacturing conditions and properties are shown in the table.

We claim:

1. The method of manufacturing insulated wire comprising the steps ofelectrodepositing a resin coating on an electric conductor, at leastpartially dissolving the electrodeposited resin with a solution ordispersion of a solid lubricant in an organic solvent therebyintroducing said solid lubricant into said electrodeposited resin tolower the friction coefficient thereof, and thereafter baking thetreated resin.

1. THE METHOD OF MANUFACTURING INSULATED WIRE COMPRISING THE STEPS OFELECTRODEPOSITING A RESIN COATING ON AN ELECTRIC CONDUCTOR, AT LASTPARTIALLY DISSOLVING THE ELECTRODEPOSITED RESIN WITH A SOLUTION ORDISPERSION OF A SOLID LUBRICANT IN AN ORGANIC SOLVENT THEREBYINTRODUCING SAID SOLID LUBRICANT INTO SAID ELECTRODEPOSITED RESIN TOLOWER THE FRICTION COEFFICIENT THEREOF, AND THEREAFTER BAKING THETREATED RESIN.